Add update log page with activity heatmap and timeline

[ImChong]

Summary

Adds a new "Update Log" page that displays a GitHub-style activity heatmap and day-by-day timeline of paper note additions and maintenance, derived from the repository's git commit history.

Key Changes

• New page: updates.html — renders an interactive update log with:

  • Statistics (total updates, note count, active days)
  • GitHub-style activity heatmap (53-week window, color-coded by activity level)
  • Filterable day-by-day timeline showing which notes were added vs. maintained
  • Full i18n support (English/Chinese)
  • Responsive design with horizontal scroll on narrow screens

• Data generation: scripts/generate_updates_data.py — new Python script that:

  • Parses git history (git log --name-status --topo-order) to track note lifecycle
  • Follows file renames and deletions to correctly attribute history to current note paths
  • Generates _data/updates.json with per-day activity and note metadata
  • Includes comprehensive test suite (tests/test_generate_updates_data.py)

• Styling: ~400 lines of CSS in assets/css/style.css for:

  • Heatmap grid layout (CSS Grid with fluid column sizing)
  • Theme-aware color ramps (VS Code blue for dark theme, arXiv red for light)
  • Timeline with vertical connector line and activity dots
  • Collapsible day sections (fold/unfold for days with >14 updates)
  • Accessible button states and ARIA labels

• Integration:

  • Homepage link to update log in index.html
  • CI workflow step in .github/workflows/deploy.yml to regenerate data on each deploy
  • Committed snapshot of _data/updates.json for local preview support

Implementation Details

• Heatmap design: Uses CSS custom properties for level colors; respects theme preference with separate light/dark palettes. Cells are square (aspect-ratio: 1/1) with responsive floor sizing (9px minimum).
• Git history parsing: Handles renames (R), copies (C), additions (A), modifications (M), and deletions (D) to correctly track notes across path changes. Scans newest→oldest to follow rename chains.
• Accessibility: Heatmap cells are buttons with proper ARIA labels; timeline uses semantic HTML (sections, lists) with visual timeline connector.
• Performance: Data embedded as JSON in page; rendering is client-side JavaScript with event delegation for filtering and expand/collapse.

https://claude.ai/code/session_01D6GD1AnohThNNJVohDkrch